Description TUNER

Technical Field

[1] Embodiments relate to a tuner.

Background Art

[2] A tuner is a device which selects and receives a desired broadcasting channel from a high frequency signal received by an antenna. The tuner can have a very high frequency (VHF) band ranging from several ten MHz to several hundreds MHz and an ultra high frequency (UHF) band ranging from several hundreds MHz to several ten GHz.

[3] The tuner is divided into a VHF tuning unit receiving a VHF band channel and an

UHF tuning unit receiving an UHF band channel. The channel received from the VHF tuning unit is divided into a VHF-L band channel and a VHF-H band channel.

[4] When the signals received via the tuner pass through an active device (for example, a field effect transistor (FET), an integrated circuit (IC), etc), interference between signals may occur. As a result, sum and difference frequency components between the received signals are generated to influence channel selection. Disclosure of Invention Technical Problem

[5] Embodiments provide a tuner that can reduce generation of interference between signals and improve channel selection. Technical Solution

[6] In one embodiment, a tuner comprises: a level attenuator attenuating a signal of a band lower than a first band; a first input tuning unit receiving a signal outputted from the level attenuator to tune a signal of the first band; and a second input tuning unit receiving and tuning a signal of a second band lower than the first band.

[7] In another embodiment, a tuner comprises: a high pass filter receiving signals of a plurality of bands and passing signals of a predetermined band or more; an intermediate frequency trap unit receiving the signals outputted from the high pass filter and removing intermediate frequency signals; a level attenuator attenuating signals of a band lower than a first band among signals outputted from the intermediate frequency trap unit; a first input tuning unit receiving signals outputted from the level attenuator to tune signals of the first band; and a second input tuning unit receiving and tuning signals of a second band among the signals outputted from the intermediate frequency trap unit.

Advantageous Effects

[8] A tuner according to an embodiment can reduce generation of interference between signals and improve channel selection. Brief Description of the Drawings

[9] Fig. 1 is a view of a tuner according to an embodiment.

[10] Fig. 2 is a waveform graph of frequency signals outputted from a VHF-H input tuning unit of Fig. 1.

[11] Figs. 3 and 4 are views illustrating channel selection characteristics of a tuner according to an embodiment. Mode for the Invention

[12] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[13] Fig. 1 is a view of a tuner according to an embodiment, and Fig. 2 is a waveform graph of frequency signals outputted from a VHF-H input tuning unit of Fig. 1.

[14] A high pass filter (HPF) 11 filters signals received from an antenna ANT to output a high frequency signal. For example, the signal outputted from the high pass filter 11 may be a signal of a band ranging from about 40 MHz to about 950 MHz received from the antenna ANT.

[15] An intermediate frequency trap unit 13 removes an intermediate frequency signal from the high frequency signal filtered through the high pass filter 11. The intermediate frequency trap unit 13 may comprise an inductor and a capacitor. For example, in the intermediate frequency trap unit 13, an inductor L21 and a capacitor C21 may be parallel-connected to one another.

[16] An UHF input tuning unit 15 receives and tunes an UHF band frequency signal from the high frequency signal in which the intermediate frequency signal is removed through the intermediate frequency trap unit 13. For example, a switching diode D21 turns on by an UHF selection switch (UHF-SW) signal, and the UHF input tuning unit 15 receives and tunes the UHF band signal. For example, the UHF input tuning unit 15 may tune an UHF band signal ranging from about 470 MHz to about 850 MHz.

[17] A VHF-H input tuning unit 19 receives and tunes an VHF-H band signal from the high frequency signal in which the intermediate frequency signal is removed through the intermediate frequency trap unit 13. For example, a switching diode D turns on by an VHF-H selection switch (VHF-H SW) signal, and thus, the VHF-H input tuning unit 19 tunes a VHF-H band signal ranging from about 170 MHz to about 470 MHz received through a level attenuator 17, inductors L22 and L23, and a varactor diode D22.

[18] The level attenuator 17 may reduces a signal level of a low frequency band in the

VHF-H band signal received from the intermediate frequency trap unit 13. For

example, the level attenuator 17 may reduce a signal level of a band ranging from about 50 MHz to about 170 MHz. The level attenuator 17 may comprise a capacitor and an inductor.

[19] For example, as illustrated in Fig. 1, the high pass filter comprising a capacitor C and an inductor L may serve as the level attenuator 17 to pass only a high frequency band signal having a predetermined band range. The capacitor C may be connected between the intermediate frequency trap unit 13 and the VHF-H input tuning unit 19. The inductor L has one end connected between the capacitor C and the VHF-H input tuning unit 19 and the other end which is grounded.

[20] A VHF-L input tuning unit 21 receives and tunes an VHF-L band signal from the high frequency signal in which the intermediate frequency signal is removed through the intermediate frequency trap unit 13. For example, the VHF-L input tuning unit 21 tunes a VHF-L band signal ranging from about 50 MHz to about 170 MHz received through inductors L24 and L25 and a varactor diode D23.

[21] The tuner according to an embodiment removes a low frequency band signal from signals received through the antenna ANT using the high pass filter 11. The tuner transmits the signal in which the intermediate frequency signal is removed through the intermediate frequency trap unit 13 to the UHF input tuning unit 15, the VHF-H input tuning unit 19, and the VHF-L input tuning unit 21. Hence, the UHF input tuning unit 15, the VHF-H input tuning unit 19, and the VHF-L input tuning unit 21 tune the received high frequency signal to select a channel of a desired frequency band.

[22] In case where the VHF-H band channel is selected, the diode D is electrically connected by a voltage supplied from the VHF-H selection switch (VHF-H SW). The high frequency signal outputted from the high pass filter 11 and the intermediate frequency trap unit 13 passes through the level attenuator 17 and is transmitted to the VHF-H input tuning unit 19. The high pass filter comprising a capacitor C and an inductor L may serve as the level attenuator 17. The level attenuator 17 attenuates a signal level of a frequency of a predetermined VHF-H band or less and passes a frequency signal of a predetermined VHF-H band or more.

[23] In the tuner according to an embodiment, as illustrated by character B of Fig. 2, the level attenuator 17 remarkably reduces the signal level of a frequency band ranging from about 50 MHz to about 170 MHz in the selected VHF-H band when the VHF-H band channel is selected. Hence, when the VHF-H band channel is selected by the VHF-H input tuning unit 19, interference generated by a signal of the band ranging from about 50 MHz to about 170 MHz may significantly reduced.

[24] In the tuner according to an embodiment, a waveform as illustrated by character A of

Fig. 2 is detected in case where the level attenuator 17 is not applied. That is, in case where the level attenuator 17 is not applied, a signal level of the band ranging from

about 50 MHz to about 170 MHz is greater than that detected in case where the level attenuator 17 is applied.

[25] If a channel frequency Fl and a channel frequency F2 are received within a VHF-L band (from about 50 MHz to about 170 MHz), and a channel frequency F3 is received within a VHF-H band (from about 170 MHz to about 470 MHz). Then, an interference signal frequency F4 generated from the sum of the channel frequency Fl and the channel frequency F2 is located around the channel frequency F3.

[26] When the interference signal frequency F4 is located around the channel frequency

F3, the frequency interference frequency F4 has an effect on the channel selection of the channel frequency F3. This will be described with reference to Figs. 3 and 4. Fig. 3 is a view of signal interference when a level attenuator is not applied, and Fig. 4 is a view of signal interference when a level attenuator is applied.

[27] Referring to Figs. 3 and 4, a signal level of the channel frequency Fl and a signal level of the channel frequency F2 are varied according to application of the level attenuator 17. When the level attenuator 17 is applied, the signal level of the channel frequency Fl and the signal level of the channel frequency F2 are reduced, and a signal level of the interference signal frequency F4 is further reduced.

[28] Since the signal level of the interference signal frequency F4 is large when the level attenuator 17 is not applied, the interference signal frequency F4 has an effect on the channel selection of the channel frequency F3. However, the signal level of the interference signal frequency F4 is very small when the level attenuator 17 is applied, it may be prevented that the interference signal frequency F4 has an effect on the channel selection of the channel frequency F3.

[29] For example, the channel frequency Fl may be 55.25 MHz, the channel frequency F2 may be 157.25 MHz, and the channel frequency F3 may be 210.25 MHz. The interference signal frequency F4 generated from the sum of the channel frequency Fl and the channel frequency F2 may be 212.5 MHz.

[30] In the tuner according to an embodiment, when the 210.25 MHz channel of the VHF-

H band is selected, the VHF-H input tuning unit 19 can tune to a signal equal to the signal in which is illustrated by character B of Fig. 2 to select the 210.25 MHz channel. Therefore, since a signal of the 55.25 MHz and a signal of the 157.25 MHz are attenuated and received, the interference signal of the 212.5 MHz can be reduced. According to an embodiment, the signal level of the interference signal can be reduced, thereby improving the selection of the 210.25 MHz channel.

[31] Any reference in this specification to "one embodiment", "an embodiment",

"example embodiment" etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is comprised in at least one embodiment of the invention. The appearances of such phrases in various places in the specification

are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.

[32] Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art. Industrial Applicability

[33] The tuner according to the embodiments can reduce generation of interference between signals and improve channel selection.